Favorite GIFs

Alternating vortices shed from opposite sides of a cylinder in flow. Shows up in everything from wind turbines to the wakes of islands.

A molecular reaction pathway passing through the highest-energy intermediate — the saddle point that separates reactants from products.

The 4D analog of a tetrahedron, projected into 3D space. The simplest regular polytope in four dimensions.

A Conway's Game of Life pattern that endlessly produces gliders. The first known finite pattern with unbounded growth.

Normal modes of vibration in a 1D crystal lattice. Different wavevectors k produce standing waves at quantized frequencies.

A chess knight visits every square on the board exactly once. Finding a closed tour (returning to the start) is a classic combinatorics problem.

亀 (turtle). No further justification required.